﻿using System;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections;
using System.Collections.Generic;
using System.Threading;

namespace WebSocket
{
    class Program
    {
        static AutoResetEvent allDone = new AutoResetEvent(false);
        static List<SocketGuidInfo> list = new List<SocketGuidInfo>();
        static void Main(string[] args)
        {
            int port = 1818;
            byte[] buffer = new byte[1024];           

            IPEndPoint localEP = new IPEndPoint(IPAddress.Any, port);
            Socket listener = new Socket(localEP.Address.AddressFamily,SocketType.Stream, ProtocolType.Tcp);
            
            try{
                listener.Bind(localEP);
                listener.Listen(10);

                Console.WriteLine("WebSocket通讯服务器启动了....");

                while (true)
                {
                    Socket sc = listener.Accept();
                    if (sc != null)
                    {
                        StateObject state = new StateObject();
                        state.workSocket = sc;
                        sc.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);

                        allDone.WaitOne();
                    }
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }

        /// <summary>
        /// 异步回调
        /// </summary>
        /// <param name="ar"></param>
        static void ReceiveCallback(IAsyncResult ar)
        {
            try
            {
                StateObject state = (StateObject)ar.AsyncState;
                Socket client = state.workSocket;
                Console.WriteLine("接受到了客户端：" + state.workSocket.RemoteEndPoint.ToString() + "数据....");

                int bytesRead = client.EndReceive(ar);
                allDone.Set();

                if (bytesRead > 0)
                {
                    if (state.workSocket.RemoteEndPoint.ToString() != "10.9.146.31:1819")
                    {
                        //握手
                        state.workSocket.Send(PackHandShakeData(GetSecKeyAccetp(state.buffer, bytesRead)));
                        Console.WriteLine("已经发送握手协议了....");

                        //接受客户端数据
                        Console.WriteLine("等待客户端数据....");
                        int length = state.workSocket.Receive(state.buffer);//接受客户端信息
                        string clientMsg = AnalyticData(state.buffer, length);
                        Console.WriteLine("接受到客户端guid数据：" + clientMsg);

                        list.Add(new SocketGuidInfo { guid = clientMsg, socket = state.workSocket });
                    }else {
                        //发送数据
                        list[0].socket.Send(PackData(list[0].guid));
                        Console.WriteLine("发送数据：“" + list[0].guid + "” 至Web客户端....");
                        
                    }

                    ////接受客户端数据
                    //Console.WriteLine("等待接受手机端认证数据....");
                    //length = sc.Receive(buffer);//接受客户端信息
                    //clientMsg = Encoding.UTF8.GetString(buffer, 0, length);
                    //Console.WriteLine("接受到手机通讯服务器端数据：" + clientMsg);

                    ////发送数据
                    //string sendMsg = clientMsg;
                    //Console.WriteLine("发送数据：“" + sendMsg + "” 至Web客户端....");
                    //sc.Send(PackData(sendMsg));

                    //Console.WriteLine("演示Over!");
               

                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }


        public class SocketGuidInfo {
            public string guid { set; get; }
            public Socket socket { set; get; }
        }

        public class StateObject
        {
            public Socket workSocket = null;
            public const int BufferSize = 1024;
            public byte[] buffer = new byte[BufferSize];
            public StringBuilder sb = new StringBuilder();
        }

        /// <summary>
        /// 打包握手信息
        /// </summary>
        /// <param name="secKeyAccept">Sec-WebSocket-Accept</param>
        /// <returns>数据包</returns>
        private static byte[] PackHandShakeData(string secKeyAccept)
        {
            var responseBuilder = new StringBuilder();
            responseBuilder.Append("HTTP/1.1 101 Switching Protocols" + Environment.NewLine);
            responseBuilder.Append("Upgrade: websocket" + Environment.NewLine);
            responseBuilder.Append("Connection: Upgrade" + Environment.NewLine);
            responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine + Environment.NewLine);
            //如果把上一行换成下面两行，才是thewebsocketprotocol-17协议，但居然握手不成功，目前仍没弄明白！
            //responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine);
            //responseBuilder.Append("Sec-WebSocket-Protocol: chat" + Environment.NewLine);

            return Encoding.UTF8.GetBytes(responseBuilder.ToString());
        }

        /// <summary>
        /// 生成Sec-WebSocket-Accept
        /// </summary>
        /// <param name="handShakeText">客户端握手信息</param>
        /// <returns>Sec-WebSocket-Accept</returns>
        private static string GetSecKeyAccetp(byte[] handShakeBytes,int bytesLength)
        {
            string handShakeText = Encoding.UTF8.GetString(handShakeBytes, 0, bytesLength);
            string key = string.Empty;
            Regex r = new Regex(@"Sec\-WebSocket\-Key:(.*?)\r\n");
            Match m = r.Match(handShakeText);
            if (m.Groups.Count != 0)
            {
                key = Regex.Replace(m.Value, @"Sec\-WebSocket\-Key:(.*?)\r\n", "$1").Trim();
            }
            byte[] encryptionString = SHA1.Create().ComputeHash(Encoding.ASCII.GetBytes(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
            return Convert.ToBase64String(encryptionString);
        }

        /// <summary>
        /// 解析客户端数据包
        /// </summary>
        /// <param name="recBytes">服务器接收的数据包</param>
        /// <param name="recByteLength">有效数据长度</param>
        /// <returns></returns>
        private static string AnalyticData(byte[] recBytes, int recByteLength)
        {
            if (recByteLength < 2) { return string.Empty; }

            bool fin = (recBytes[0] & 0x80) == 0x80; // 1bit，1表示最后一帧  
            if (!fin){
                return string.Empty;// 超过一帧暂不处理 
            }

            bool mask_flag = (recBytes[1] & 0x80) == 0x80; // 是否包含掩码  
            if (!mask_flag){
                return string.Empty;// 不包含掩码的暂不处理
            }

            int payload_len = recBytes[1] & 0x7F; // 数据长度  

            byte[] masks = new byte[4];
            byte[] payload_data;

            if (payload_len == 126){
                Array.Copy(recBytes, 4, masks, 0, 4);
                payload_len = (UInt16)(recBytes[2] << 8 | recBytes[3]);
                payload_data = new byte[payload_len];
                Array.Copy(recBytes, 8, payload_data, 0, payload_len);

            }else if (payload_len == 127){
                Array.Copy(recBytes, 10, masks, 0, 4);
                byte[] uInt64Bytes = new byte[8];
                for (int i = 0; i < 8; i++){
                    uInt64Bytes[i] = recBytes[9 - i];
                }
                UInt64 len = BitConverter.ToUInt64(uInt64Bytes, 0);

                payload_data = new byte[len];
                for (UInt64 i = 0; i < len; i++){
                    payload_data[i] = recBytes[i + 14];
                }
            }else{
                Array.Copy(recBytes, 2, masks, 0, 4);
                payload_data = new byte[payload_len];
                Array.Copy(recBytes, 6, payload_data, 0, payload_len);

            }

            for (var i = 0; i < payload_len; i++){
                payload_data[i] = (byte)(payload_data[i] ^ masks[i % 4]);
            }
            
            return Encoding.UTF8.GetString(payload_data);
        }


        /// <summary>
        /// 打包服务器数据
        /// </summary>
        /// <param name="message">数据</param>
        /// <returns>数据包</returns>
        private static byte[] PackData(string message)
        {
            byte[] contentBytes = null;
            byte[] temp = Encoding.UTF8.GetBytes(message);

            if (temp.Length < 126){
                contentBytes = new byte[temp.Length + 2];
                contentBytes[0] = 0x81;
                contentBytes[1] = (byte)temp.Length;
                Array.Copy(temp, 0, contentBytes, 2, temp.Length);
            }else if (temp.Length < 0xFFFF){
                contentBytes = new byte[temp.Length + 4];
                contentBytes[0] = 0x81;
                contentBytes[1] = 126;
                contentBytes[2] = (byte)(temp.Length & 0xFF);
                contentBytes[3] = (byte)(temp.Length >> 8 & 0xFF);
                Array.Copy(temp, 0, contentBytes, 4, temp.Length);
            }else{
                // 暂不处理超长内容  
            }

            return contentBytes;
        }  
    }
}
